Just to give some wider context, because it's boring seeing this called a 'Rawk thing', of Labour voters from 2017 general election asked to choose between May, Corbyn, and don't know:
53% said Corbyn would be the better PM
10% said May is the better PM
35% couldn't pick between them
Working class voters (ie C2DE)
39% couldn't pick between the two
35% said May is the best PM
23% said Corbyn would be the better PM
People who intend to vote Labour at the next general election
68% reckon Corbyn would be the better PM
3% reckon May is the better PM
27% can't choose between them
(Yougov, 22/23 October 2018,
pdf)